An MIMO (Multiple Input Multiple Output, multiple input multiple output) technology is one of the most important technologies for improving spectral efficiency of a wireless system. In an MIMO system, generally, a good transmission effect can be achieved only when a transmitter learns a channel, while in an FDD (Frequency Division Duplexing, frequency division duplexing) system, generally, a receiver feeds back channel state information to a transmitter. Therefore, which method is adopted to feed back the channel state information is a hotspot in a standard design.
In the prior art, when the channel state information is fed back, first a channel eigenvector is quantified by performing weighted combination on multiple DFT (Discrete Fourier Transform, discrete Fourier transform) codebooks, and then a first-level code word is fed back in a relatively long period, where the first-level code word includes a channel statistical central angle, an offset value relative to the central angle, and the number of DFT vectors contained in the first-level code word. In a ULA (Uniform Linear Array, uniform linear array) placed horizontally, a DFT code word is generally determined by a horizontal pointing angle, and horizontal pointing angles corresponding to multiple DFT code words are continuous, so the number of the code words and an offset value of each code word may be used to represent the DFT vector. Then a second-level code word is fed back in a relatively short period, and the code word may be selected from a GLP (Grassmannian Linear Packing) or RVQ (Random Vector Quantization) codebook.
However, when the prior art is adopted to feed back the channel state information, the DFT code word of the ULA only relates to a horizontal dimension and only a single-layer code word technology is adopted; when an antenna array is multi-dimensional and a code word vector has multiple dimensions, the prior art is inapplicable.